1. Field of the Invention
The present invention relates to an elevator system, and more particularly to an improved guide roller apparatus for an elevator system for preventing an elevator car from shaking horizontally during an operation of the elevator system by transformations of guide rails disposed vertically along side walls in an elevation shaft.
2. Description of the Background Art
As shown in FIG. 1, in a general elevator system, an elevator car 1 for carrying passengers or luggage is suspended by a plurality of ropes 2 engaged at a top portion thereof. The ropes 2 are connected to a driving apparatus (not shown) which allows the elevator car 1 to move vertically in an elevator shaft 3. Here, the driving apparatus (not shown) is disposed at an upper portion of a building equipped with the elevator system.
A plurality of guide rails 4 for guiding the elevator car 1 are vertically fixed along sidewalls of the elevator shaft 3. A plurality of guide rollers 5 running along the guide rails 4 are engaged to a frame (not shown) fixed to each corner the elevator car 1.
The mechanism of the guide rollers 5 will now be described with reference to the accompanying drawings.
As shown in FIGS. 2A-2C and C, the conventional guide roller apparatus includes a lever 7 having a lower portion hingedly engaged to a flat type frame 6 fixed to each corner of the elevator car 1, and an upper portion connected to a rotation shaft 5a of the guide roller 5, thereby supporting the guide roller 5 on the rotation shaft 5a. Here, an insertion hole 7a is formed at a lower portion of the lever 7.
A side end portion of the frame 6 there is engaged a vertical plate 10 facing against the lever 7 and having a predetermined height.
A side end of a compression coil spring 8, serving as an elastic support member connected between the lever 7 and the vertical plate 10, is horizontally connected to an upper side portion of the lever 7. Also, a spring support 11 has a side portion coupled to another end portion of the compression coil spring 8 and another side portion horizontally connected to an upper side portion of the vertical plate 10.
A stopper support 13 acts as an interruption member and is provided between the lever 7 and the vertical plate 10. An end portion of the stopper support 13 is horizontally connected to a predetermined intermediate portion of the vertical plate 10, and another end portion of the stopper 13 is passed through the insertion hole 7a formed in the lever 7.
A stopper 9 is spaced by an interval .delta. from the lever 7 so as to restrict a horizontal movement of the guide roller 5 to a predetermined displacement, for thereby preventing the guide roller 5 from escaping the guide rail 1 with regard to the stopper support 13. Here, the interval .delta. is significantly small.
With reference to FIG. 4, the guide roller apparatus according to another example of the background art will now be described.
At each corner of the elevator car 1, a plurality of vertical frames 14 are fixed by bolts and nuts (not shown) to an upper frame 12 and a lower frame 13.
A vertical roller 15 which runs along the guide rail 4 is connected to the vertical frame 14. A pair of horizontal rollers 16 are connected to each other, symmetrically with respect to the vertical roller 15.
A stable pin 19 is inserted into the vertical frame 14 with regard to a roller rotation shaft on which the vertical and horizontal rollers 15, 16 are rotated. An end portion of the stable pin 19 is fixed to another vertical frame (not shown). Onto another end portion of the stable pin 19 a coil spring 20 is fitted one end of the coil spring 20 abuts a compression seat 23 to confine the coil spring 20. A stable nut 24 is connected to a side portion of the compression seat 23 to fix the compression seat 23 thereto.
An end portion of a stopper support 17a (communicating with the vertical frame 14 and fixed to another vertical frame (not shown) is connected below the roller rotation shaft 18 so as to prevent the elevator car 1 from shaking excessively. The stopper 17 is spaced by a predetermined interval from the vertical frame 14 and is connected to another end portion of the stopper support 17a.
The thusly constituted conventional guide roller apparatus may vibrate horizontally during its operation for a variety of reasons, including poor installation of the guide rail 4, an aged connection member, and varied surface roughness.
Such horizontal vibrations are transferred through the guide roller 5 to the elevator car 1 by the guide rail 4. Here, an exciting force caused by the horizontal vibration is evenly distributed to each of the guide rollers 5 disposed at the respective corners of the elevator car 1, when the guide rail 4 is in good condition, the elevator car 1 is well balanced without tilting to one side thereof, thereby being buffered by the compression coil springs 8, 20 of the guide roller 5.
However, if the guide rail condition is not good and the elevator car is excessively tilted to one side the exciting force applied to the elevator car 1 increases by the unbalance of the elevator car 1, therefore, the lever 7 or the stoppers 9, 17 (spaced by an allowed movement displacement .delta. from the vertical frame 14) restricts the horizontal movement of the lever 7, the vertical frame 14 and the guide rollers 5.
As shown in FIG. 8, the support force of the guide roller 5 is good in an interval P.sub.0 -P.sub.A (as shown by line A) and in an interval P.sub.0 -P.sub.B (as shown by line B), which are supported by the compression coil springs 8, 20. Therefore the exciting force caused by deformations of the guide rails 4 when the elevator car 1 runs along the guide rails 4 in the elevation shaft 3, cause deflection of the coil springs 8, 20 attached to the guide rollers 5.
That is, the vibration sensed by the passengers aboard the elevator car 1 is decreased.
However, the spring constant values K of the coil springs 8, 20 should be decreased so as to improve a vibration buffering effect of the coil springs 8, 20. Therefore when an unbalanced load or an intensive load is charged into the elevator car 1, the elevator car 1 excessively tilts so that an interruption between the elevator car 1 and other devices. At the same time, the guide roller 5 disposed on the elevator car 1 may deviate from the guide rail 4 disposed vertically in the elevation shaft 3, thereby causing a safety problem.
That is, as shown in line A of FIG. 8, when the displacement of a central portion of the guide roller 5 with regard to a supporting force P.sub.A of the coil springs 8, 20 of the guide roller 5 surpasses a value .delta.a, the tough stoppers 9, 17 become operable, thereby dissipating a horizontal vibration of the elevator car 1. Also, when the guide roller 5 travels through between an supporting force interval P.sub.0 -P.sub.A according to line A in FIG. 8, or an interval less than the displacement .delta.a of the center of the guide roller and the interval which is more than the supporting force P.sub.A, (and which displacement at a central portion of the guide roller is more than displacement .delta.a) the variation of an abrupt spring characteristic may deteriorate the vibration of the elevator car.
In order to solve the above-described problem, when coil spring 8 having a large spring constant value K is employed, a poor condition interval P.sub.A -P.sub.B as well as a good condition interval P.sub.0 -P.sub.A may be supported by the coil spring. Here, an exciting force which occurs due to transformations or deformations of the guide rails may be buffered.
However, when the guide rails are in good condition, the constant value K of the coil spring becomes increased, thereby generating a poor vibration characteristic.